1. Field of the Invention
This invention relates to data storage systems employing magnetic disk drives for use in data processing systems. More specifically, the invention pertains to magnetic disk drives having reduced packaging size, increased storage capacity, and faster access time.
2. Prior Art
A data storage system of the type herein described typically includes one or more rotating circular magnetic disks having recording surfaces on opposite sides of the disks. Information is recorded on these surfaces as a plurality of concentric tracks containing user data and other types of information. At least one read/write head is utilized for transferring information to and from each of the different recording surfaces of the disks. An actuator mechanism of some type is employed to move the heads in unison to position them at selected different radial track locations on the disk surfaces.
Most current disk drives employ some type of servo positioning information recorded on the disks to assist in first locating and then maintaining the heads at the desired radial track location on the disk surfaces. The locating operation is referred to as track seeking, and the maintaining operation is referred to as track following.
Those portions of the disk recording surfaces which do not contain servo positioning information are dedicated to stored data utilized by the using data processing system. The servo positioning information may be interleaved with user data in circumferentially spaced sectors on each of the recorded tracks, or, alternatively, all servo information may be contained on a dedicated servo surface of the recording medium, while the user data is contained on the remaining surfaces of the recording medium. In a magnetic disk drive of the former type, commonly called a sector servo drive, servo positioning information can be read by the same magnetic head that reads the user data. The arrangement and pattern of the servo positioning information may be varied according to the particular track seeking and track following algorithm employed by the disk drive system.